I'll be honest and say I haven't read this article yet, was brought in by @nichole's comment and I would have to agree. We drove tons of traffic paid and unpaid from StumbleUpon for a startup I was consulting for and it was basically all vanity metrics.

If temporary big numbers in Google Analytics excites you or seeing your Alexa Ranking go up for a while, use StumbleUpon. But if true growth is what you're after, hit the drawing boards to figure out how you can get more valuable visitors in your target audience to your site or how to convert more of the audience that you're already getting (CRO).

I would love to see a case study on how you can turn StumbleUpon traffic into a useful asset for your business, not just traffic.

I've crashed a site before by driving a massive amount of traffic from StumbleUpon, and found that the traffic was irrelevant. It didn't lead any increase in actionable metrics. The only thing that it was slightly useful for was link building - several StumbleUpon users posted a link to the page from their Tumblrs but even then the links were all from the same domain.

I've used Stumbleupon to get traffic to sites to sell "ad space" (links) and it works like a charm.

1) Purchase a recently dropped domain with good PR, DA, and a nice link profile in a niche that you know buys links. 2) Use Wordpress CMS and an automated post that pulls from feeds or YouTube. Create a whole bunch of categories and set each to post around 10x per day at mimimum. 3) Use a plugin or script that auto-submits each post to StumbleUpon. You can even create around 10 stumbleupon accounts and have each post submit to each account. 4) Wait til your alexa get's low enough to sell links. You can also monetize the traffic with adsense. If you get enough clicks on adsense I noticed that you'll even start to get good SE traffic too.

Not really a growth hack for a startup but if you were looking to make some easy side cash, this strategy has worked for me as well as friends that I helped.

In a nutshell, stumbleupon traffic is great of strategies like the one mentioned above. I don't think it's viable for customer acquisition.